The present invention relates to reflector assemblies and, more particularly, to reflector assemblies for use with low voltage emergency lights such as are employed in aircraft.
Commercial aircraft have dual cabin interior lighting systems. A conventional lighting system is powered by the generators driven by the aircraft engines while a back-up emergency lighting system is powered by electrical energy storage devices, such as batteries. The power output of the back-up electrical energy storage systems is substantially less than the power output of the conventional power source for energizing the conventional lighting system. In accordance with current industry standards, a back-up lighting system employing an incandescent bulb is normally required to operate at a relatively low voltage, on the order of 21/2 volts, and yet must have a light output over a 40 square inch area at a location 52 inches from the light source of 0.05 foot candles at all locations over the entire 40 square inch area. Light sources that produce a greater illumination than required in the center of the area and a lesser illumination than required toward the periphery of the area are inadequate to meet industry standards and thus unacceptable for the intended purpose.
Prior art reflector assemblies have employed a variety of reflective or semireflective light diffusing coatings in a reflector cavity in which the incandescent light source is housed. For example, one type of reflector cavity coating has a semireflective, glossy white coating throughout the cavity. This coating produces an adequately diffused light over the required 40 square inch area to meet the current industry standards. However, improved light distribution and better illumination from the same power source is always being sought. One attempt to improve the intensity of the illumination over the entire area has been to provide a highly reflective, mirror-like coating over the entire reflective cavity. This highly reflective structure results in a spot lighting effect at the center of the 40 square inch area with reduced illumination at the periphery of the area. Thus, the fully reflectorized cavity does not produced the desired result.
It is therefore a broad object of the present invention to increase the diffused light output otherwise provided by a standard incandescent bulb and power source for use in emergency lighting systems. Further objects of the present invention are to improve the light output of such emergency lighting systems without creating a spotlighting effect, that is, to maintain an evenly diffused light over the entire illuminated area; to retain a standard diffusing lens in a reflector assembly without the necessity for machining or manufacturing a special lens structure; and to increase the output of such lighting systems with little or no modification to the reflector assemblies presently utilized in such lighting systems.